PROJECT SUMMARY The investigators will combine experimental studies with computational simulations to uncover the neural circuit mechanisms underlying taste choice behavior. A fundamental question to be addressed is how the neural activity induced by a given taste is impacted by the recent sampling of another taste and/or by the expectation that another taste is forthcoming. We will analyse data produced from ensemble recordings of neural activity and make use of optogenetic techniques that alter neural activity, to further our work on how specific features of such activity impact behavior during a decision making task. These data will provide fuel to our modeling efforts, with which we will produce a framework that can generalize to other sensory modalities, whenever decisions are based on a consideration of one stimulus at a time (even if two stimuli are present) rather than on a parallel processing of two or more stimuli simultaneously?that is, this novel framework will allow us to understand the behavior of animals when faced with a choice between any two separate stimuli. Thus, a transformative aspect of the research will be the development of a new framework for the analysis of decision-making when the choice to be made is whether to stick with the current stimulus or to switch to another. In such decision making tasks, which are ubiquitous in natural settings, the stimulus itself is chosen by the subject rather than being controled by the experimenter. Our recordings of the animal's behavior simultaneously with its neural activity allow us to tightly constrain these first dynamic models of such a process. Taste is an important, albeit underused, modality for addressing issues of sensory processing, in that it has a strong connection to behavior?indeed it is well-nigh impossible for an animal to sample a taste without a behavioral response. Moreover, given that tastants can be intrinisically hedonic or aversive, animals are internally driven to make responses and will do so without the months of training?which inevitably rewires the brain?required for animal training in behavioral tasks based on other sensory modalities. Therefore taste is ideally suited to the study of naturalistic decision making.